In any Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) Network, such as Wireless LAN, one needs to be able to control when to transmit or not. This is accomplished by observing the media used, and trying to transmit when nobody else is using the media.
One important function in this type of Access method is the Back-off function. In a CA (Collision Avoidance) system, it is the job of a transceiver/transmitter (TX) scheduler to observe a shared media and, based on the observations, find a transmit opportunity for the own station.
In 802.11 networks, i.e. networks supporting and working according to the IEEE standard 802.11, the transceiver/transmitter TX dispatcher (i.e. TX scheduler) has to consider the following:                Energy detect on the media originating from non-802.11 stations (microwave-ovens, or Bluetooth devices for example).        Transmissions from other 802.11 stations.        
The TX-dispatcher constitutes a conceptual state-machine that takes the above entities as input. By compiling the physical events on the channel with a timestamp related to the respective event, and by examining the content of radio messages sent by other stations, the TX-dispatcher decides when to dispatch a pending transmission to the shared media.
The IEEE 802.11 standard defines a set of rules that strictly and unambiguously controls when a station may access the media for transmission. The problem with this set of rules is that the decision logic becomes complex enough to require CPU processing, while the timing requirements are hard enough to be more suited for hardware processing.
The complexity of the decision logic has been the killing argument for manufacturers of 802.11 chips to choose to implement the TX-dispatcher state-machine in software only.
However, in practice the time course of a media (channel) is fragmented in many ways, which causes severe problems to design a software fulfilling said standard for transmission.
The downside of implementing the state-machine in software is because:                Power consumption is increased, as the CPU has to deal with very high-frequency events.        The performance requirement on the CPU is increased (Higher clock frequency (=higher power consumption) or more advanced CPU (=more expensive solution) is required).        
As can be seen above, this is a simple task from a software point of view, but the interrupts can be triggered quite frequently, and there is a lot of time uncertainty.
To address the above stated problem, it has been suggested in the prior art to divide an overall TX-scheduler state-machine into two different state-machines: One first TX-scheduler state-machine (FTSM), executed in software, which controls and administers one second TX-scheduler state-machine (STSM) executed in hardware.
In patent application WO 01/86434 A2 a state machine is shown, implementing a communication protocol such as the Bluetooth protocol. Furthermore, a synchronous Time-Division Duplex (TDD) scheme is described, wherein decisions and state transitions are made periodically in specific points of time. The document only describe a synchronous system and is not adaptable to an asynchronous system wherein avoidance of collisions in a shared media is essential.
The patent application EP 1 333 620 A2 discloses a method for implementing a plurality of backoff counters in a single hardware backoff counter. When state transitions are made, either the software or the hardware adjusts and compares the backoff counters values.
However, the complexity of said known methods and systems are considerable as they require complex hardware and software solutions, wasting a lot of CPU time and battery power.